In addition to the industrial fiber laser systems, Futonics offers various F-Theta lenses for 2 µm lasers that can be purchased separately.

The new Futonics product line of F-theta lenses is based on crystal lenses made of zinc selenide and calcium fluoride. Effective focal lengths of 170 mm and 345 mm are available.
High-performance applications at a wavelength of 2 µm require absorption-free lens materials. Most quartz materials absorb due to intrinsic OH molecules at a wavelength of 2 µm. At several hundred watts of laser power, this residual absorption heats the lens and causes at least a distortion of the front heat waves. In extreme cases, the material even tears. Not so with the F-Theta lenses from Futonics.

• 

Specifications	F-TO 170/2000	F-TO 345/2000
Design wavelength	1940-2050 nm	1940-2050 nm
Effective focal length	170,2 mm	344,8 mm
Max. Inlet diameter	10 mm	20 mm
Optical scanning angle	±22°	±24°
Working distance	198,7 mm	316,7 mm
Scanning area *	90 mm x 90 mm	205 mm x 205 mm
Lens material	ZnSe, CaF2	ZnSe, CaF2
Spot diameter focus	47,6 µm	88,6 µm

* For a system with two mirrors with mirror distances from the lens housing: 19.7 mm / 35.7 mm